JUt- Bulletin No. 1 January 1911 Second edition January 1912 Oregon State Bureau of Mines HENRY M. PARKS DIRECTOR ROAD MATERIALS IN THE WILLAMETTE VALLEY The bulletins of the Bureau of Mines are sent free to all residents of Oregon who request them. Series 1] Entered as second-class matter November 27, 1909, at the postoffice [No. 46 at Corvallis, Oregon, under the act of July 16, 1894. UNIVERSITY OF ILLINOIS LIBRARY AT URBANA- CHAMPAIGN m 2 2 >531 Reconnaissance Map of the Willamette Valley Showing available outcrops of road materials in the more densely populated portion. Road Materials the Willamette Valley OREGON AGRICULTURAL COLLEGE PRESS CONTENTS, \*\ \ ^ Introduction. General geology of the Willamette Valley. Physical properties of rock-making minerals. Rock classification. Igneous rocks — Structure. Mineral content. Corelation of mineral content and structure with physical prop- erties. Comparative value for road materials. Sedimentary — Structures. Comparative value for road materials. Metemorphic — Structure. Comparative value for road materials. Rock weathering and its effect from standpoint of road material. Description of laboratory test. Discussion of the value of laboratory tests. Road material situation by counties — Benton. Clackamas. Lane. Linn. Marion. Multnomah. Polk. Tillamook. Washington. Yamhill. Suggestions for selecting quarry sites. Gravels in the Willamette river. General Observations. Cost data. Summary and conclusion. Plate i. — Graphic Granite. Note the parallel arrangement of the quartz and feldspar crystals 5 INTRODUCTION, It has often been stated that Oregon has more good road material than any other state, a statement which is doubtless true. The fact still re- mains, however, that the road builders of our state are usually not suf- ficiently well versed in principles of geology to be able to distinguish excellent material from that of medium quality, nor the material of me- dium quality from the poor material. It is also a fact that the road builder will often transport his material for long distances at an extra cost when as good or better material is close at hand. The main purpose of this bulletin is to set forth in plain language the fundamentals of geology as they apply to the principles of scientific road building so that the road builder, by appropriating these principles, will be able very largely to pass judgment without having to be at the mercy of another’s opinion or judgment. This bulletin is not intended to be a scientific treatise in geology, but is written expressly for the road builder, using only the principles of geology in so far as they can be applied to the intelligent selection an 1 handling of road materials. The field observations which form the basis of this report were made by H. M. Parks, assisted by S. W. French and H. E. Cooke, and was com- pleted during the summer vacation months of July, August and Septem- ber of 1910. The area covered in this reconnaissance includes only the more densely populated portion of the Willamette Valley, which is in general the main floor of the valley, including only the first rim of foothills as a boundary. It was thought that a more extensive survey far back Into the tributary valleys and foothills is not warranted at this time for three reasons- First, because it was found that these ultra rural communities are sup- plied with good outcrops in much greater quantities than the valley proper; and, second, because of greater immediate demand for road materials in the central valley; and, third, because of lack of funds anl time for carrying on the work. More than five hundred different out- crops were examined in the area indicated, average types of these were selected and sent in to the college for more detailed examination. The map accompanying this bulletin is not intended as a geological map and does not show all the outcrops of rock in the area covered, but it is intended to show only the approximate areas in which available out crops of good road materials are found, as well as indicating the ones to be shunned. The map will be very serviceable in showing the general distribution of available materials, not only in the valley as a whole, but in each county or locality. Owing to the inaccuracy of any available base maps of the area treated, it was found impossible to locate these out- crops with extreme accuracy. For this reason, after the approximate location is determined, the reader should depend upon the locality de- scription for more accurate information. This will be found under Road Material Situation by Counties. 6 We wish to acknowledge our appreciation for the courtesies shown by the railroad companies of the valley in furnishing transportation by tho different county courts, which aided materially in defraying local ex- penses; by the Oregon Good Roads association in assisting in creating favorable sentiment toward the carrying out of this work, and by M. O. Eldridge of the Department of Good Roads, Washington, D. C., for photo- graphs, as well as others who furnished illustrative material. We also wish to express our appreciation for the faithful work of Messrs. S. H. Graf, P. A. Jones and M. A. Nickerson in making laboratory tests. GENERAL GEOLOGY OF THE WILLAMETTE TALLEY. A few of the general principles of geology as applied to the Willamette Valley will not be out of place, and may be of some service in the interpretation of the material which follows in this bulletin, as well as accounting for some of the more important surface features, such as topography, general character of soils, etc. The main trough of the Willamette Valley is a structural valley; that, is, it was formed originally by mountain making foldings approximately parallel to each other on either side, having the valley proper as a trough between the two folds. These folds were exaggerated at the same time and also later by the addition of a large amount of volcanic material poured out from numerous volcanoes distributed along each of the folds. The first of these two folds to appear above the ocean level was the Cascades on the east of the valley. They were developed during the Eocence period, and during this period, as well as a large part of the Miocene period which followed, formed the Pacific Coast, or in other words, formed the western border of the continent at this latitude during that time. During the Miocene period the coast range was pushed up from the sea floor on the west of the valley, but was not fully developed until the Pliocene period which followed. Still later during the Pleis- tocene period the Willamette Valley was a bay or sound similar to the Puget Sound of today. A considerable amount of fine sediment was washed from these hills during this time and distributed over the floor of the bay. This is probably the principal source of our deep heavy clay soils so general over the main floor of the valley. During the time since these two mountain ranges have appeared above the ocean, until the present time the weathering agencies such as frost, wind, rain, etc., have been hard at work upon them, wearing, rotting and carrying them away and we find them today ramified by a network of streams which have carved deep canyons upon their slopes and in that way exaggerating to a large extent the ruggedness of the original topography of these mountain slopes. In as far as the agencies of decay such as ground water, frost, etc., have been able to keep in advance of the transporting agencies such as running water, wind, etc . just that far has the soil been able to accumulate upon these hillsides. Whenever the transporting agencies are able to keep pace with the decaying agencies of the rocks, there we find the rocks bare or as we 7 say, outcropping. On this account the southwest slopes of our hills in the Willamette Valley have thinner soils and more outcrops than the northwest slopes. This is due to the prevailing winds from the south west and in a great many cases the soils are carried away as fast as formed. Again we find outcrops almost universally upon the steep slopes of stream canyons, where the soil is carried away as fast as formed. The Willamette Valley is most fortunate in having a goodly supply of rocks, which are exceptionally well adapted for road materials, as well as being well distributed over the valley. We have already seen that these mountain ranges on either side of the valley are largely composed of volcanic material. These volcanic materials are very largely basic lavas and form the class of rocks which are usually known to the road builder as “trap” or “trap rock”. From a petrographic stand- point they form the basalts and diabases. As will be seen later these rocks as a class, from the standpoint of road materials, are as good as the best. A large part of these trap rocks are surface lava flows whil^ some are found as dikes or intruded sheets. These rocks are found mostly in the foot hills where they have been exposed by erosion, thus making a more or less continuous rim around the main floor of the valley. Aside from this rim or boundary of outcrops, we find numerous buttes scattered promiscuously over the valley, nearly all of which are of volcanic origin and are composed of basalt. As types of these might be mentioned Knox and Peterson Butte in Linn county, Skinner’s and Gillespie Buttes in Lane county or Kelley and Rocky Butte in Multnomah county. Some of these buttes have a certain amount of sedimentary rocks in places on the surface, but the main mass is basalt. PHYSICAL PROPERTIES OF ROCKMAKING MINERALS. It is evident at the outset that the physical properties of rocks will be dependent to a large extent, upon the physical properties of the most important minerals of which they are composed, size, and shape of its constituent mineral grains. Fortunately the number of important rock making minerals are few and in the discussion of these, we will attempt to group them as far as possible, putting those with similar physical characteristics in a group. Probably the most important of all rock forming minerals is Quartz. Its composition is pure silica. It is the hardest of all rock making minerals which we will discuss. It is a comparatively tough mineral on account of having no cleavage; that is, it has no tendency to break in one direction more than in another. As a result it has a glass like fracture and breaks in curves instead of in planes. Quartz is very widely distributed in nature occurring more or less in nearly all rocks except the basic igneous ones, but from a road material standpoint it is most important in the acid igneous rocks and sandstones. From the standpoint of toughness and hardness it is probably the best rock forming mineral known. What better recommendation as a road material 8 mineral could be asked than the fact that we find it the most resistant mineral in nature’s abrasion test, as is evidenced by the large amount of it found in the sand on the sea beach, it being almost the only one which is able to survive the severe grinding action of the waves. The Feldspars are probably the next in importance as rock making minerals. We will discuss these as a group because of their like characteristics. They are somewhat inferior in hardness to quartz, about the same in hardness as the pen knife. All of the feldspars are comparatively brittle. This, to a large extent, is due to the fact thst these minerals have a natural cleavage in two directions at right angles to each other or nearly so, which means that each crystal of feldspar Pirate 2. — “Boulders of weathering,” showing how round boulders are formed from angular blocks. no matter how tiny, has two directions of easy breaking at every microscopic point in its mass. On this account they will be more easily broken up under impact or abrasion than they would otherwise be. Another reason which makes for easy breaking in the feldspars is that one of its directions of cleavage or easy breaking is at right angles to the long direction of the crystal, making an easy breaking plane in the direction of greatest stress. The feldspars are found in most of the igneous rocks but occur in large proportions in the more acid ones. The Pyroxenes and Amphiboles are two classes or groups of minerals which are so nearly alike in their physical characteristics that they will be discussed in this connection under one head. They have about the same hardness as the feldspars, are dark in color, usually dark green black or brown. These minerals are found in nearly all igneous rocks but are more plentiful in the more basic, dark colored ones. In fact 9 the dark color of the more basic igneous rocks is due largely to the presence of these minerals in large amounts. They also occur in schists. These minerals have two directions of cleavage, the pyroxenes at about 90 degrees and the amphiboles at about 125 degrees. However since their cleavage directions are parallel to the long direction of their crystals they resist breaking and are tougher than the feldspars. The Mica group is of considerable importance as a rock making min- eral, occuring to a greater or less extent in all the igneous rocks, and it becomes most important in a large number of metamophic rocks Mica is a soft mineral, being only a little harder than the finger nail, it has a very perfect cleavage in one direction. Although the cleavage flakes are very tough and elastic, this property is more than offset by the easy cleavage and soft nature of the mineral. On the whole the micas would tend to be a detriment in any rock, considered from the sandpoint of road material, causing the rock to be inferior in toughness and wearing quali- ties. Calcite and Dolomite as primary minerals are the principal constituents of all limestones and marbles, and occur sometimes as the cementing material between the sand grains of a sandstone. These minerals are but little harder than the micas. Because of their soft nature, as well as because of the fact that their cleavage is in three directions, at angles of 105 degrees to each other, they are very brittle and friable. Conse- quently they do not possess physical characteristics which would recom- mend them as road materials. Secondary Minerals, including such minerals as kaolin, chlorite calcite, serpentine, talc and limonite, may in this discussion be included to ad- vantage in one group. Secondary minerals are those which result from the alteration of previously existing minerals by weathering or other alteration agencies. In general, they are soft friable minerals whicu crumble easily under impact or abrasion. These minerals cannot be ad- vantageous in any road material except as they assist in the binding or cementing quality of the rock in which they occur. The soft and friable nature of all weathered rocks as compared with their respective fresh unaltered ones, is very largely due to the presence of these secondary minerals. The only exception to this general rule would be in the case of a few deep-seated alteration products or secondary minerals, such as hornblende, which might increase the rock’s toughness. The following is a brief classification of rocks generally accepted by all geologists: I. Igneous — 1. Intrusive (plutonic). a. Granite. b. Syenite. c. Diorite. d. Gabbro. 2. Extrusive (volcanic). a. Rhylite. 1-2 10 b. Trachyte. c. Andesite. d. Basalt and diabase. II. Sedimentary — 1, Calcareous. a. Limestone. 2. Siliceous. b. Conglomerate. c. Sandstone. d. Chert (flint). III. Metamorpliic — 1. Foliated. a. Gneiss. b. Schist. 2. Nonfoliated. a. Slate. b. Quartzite. c. Marble. In order to discuss the physical properties of rocks as to their struc- (v •' rr ngement of their respective minerals, it will be necessary r.o give a brief classification of rocks in general and enter to some extent into their respective modes of origin. According to their mode of origin and the position of the masses with respect to the earth’s crust and with each other, rocks naturally divide themselves into three main groups, divisions which are recognized by practically all geologists. These are Igneous rocks made by the solidifi- cation of molten materials; the Sedimentary or bedded rocks formed by the precipitation of sediments in water, as well as the aeolian, or win ! formed deposits, and the Metamorpliic rocks, those produced by the sec- ondary action of certain geologic processes upon other igneous or sedi- mentary rocks by which their original characters are wholly or partly obscured and replaced by new ones. IGNEOUS ROCKS. The igneous rocks are classified both from the standpoint of their structure and mineral content. We will take up first the most important phases of their structure because this is an important factor in the dis- cussion of their wearing qualities. STRUCTURE OF INGEOUS ROCKS. Most igneous rocks are made up of interlocking crystals of different minerals. These crystals may be so small that they cannot be readily distinguished by the eye, or they may be large and easily seen, or some may be large and some small. If they are large enough to be distinct to the unaided eye they are termed coarsely crystalline or coarse grained. Some igneous rocks look like glass. In fact they are glass, and like manufactured glass they have solidified from a liquid so suddenly that the crystals have not Imu a^e to 6 iow. Such rock is termed volcanic glass or obsidian. Some igneous rock is made up partly of glass and partly of crystals, and between the rock, which is wholly glass, and that which is wholly crystalline, there are all gradations depending upon che conditions under which it solidified. All liquid lava contains the materials from which crystals may be formed under proper conditions. Volcanic rocks composed largely of glass may be either very compact or porous. Porous rock is really a sort of solidified lava froth and the pore spaces in the rock are the spaces occupied by gases when the lava hardened. Pumice contains the same material as obsidian, one being porous and the other compact. Scoria or Cellular basalt is the same material as dense besalt, one being porous while the other is compact. All igneous rocks are supposed to have solidified from a molten mass. There are a number of factors which influence the structure or grain of igneous rocks, but probably the most important are rate of cooling and pressure. If the molten mass is under great pressure and a long time is involved in making the change from the liquid to the solid state, the rock will be coarse grained; that is, made up of large crystals; conse- quently, the rocks which solidify deep down in the crust of the earth are coarse grained. If on the other hand the molten mass is suddenly chilled and under little pressure, we find the resultant rocks are glasses or else dense or microscopically fine grained; these rocks we find usually as the lavas which are forced out upon the surface of the earth. Sometimes these molten lavas do not reach the surface of the earth but are thrust into or between layers of the crust of the earth and cooled under moderate pressure and with moderate rapidity. We would therefore expect to find them and do usually find them intermediate in grain, or structure, al- though we sometimes find them dense and fine grained and sometimes rather coarse grained. MINERAL CONTENT OF IGNEOUS ROCKS. Igneous rocks are also classified according to their mineral content, and as we have already found that the different rock making minerals vary widely in the physical properties which affect their wear, it will be necessary to get in mind the main differences in the mineral make-up of igneous rocks. The following table will give an approximate idea as to the amount of the different rock making minerals in each of the common types of igneous rocks: Coarse grained. Feldspars Quartz Amphiboles & Pyroxene Mica Per cent Per cent Per cent Per cent Granite 50-60 25-35 0-15 5-15 Syenite 60-30 0- 5 0-15 5-15 Diorite 30-50 0-10 25-40 5-10 Gabbro 25-45 0 30-50 5-10 Rhyolite 40-55 10-20 0- 5 5-10 Andr-dte 35-55 0 5-20 5-10 12 CORELATION OF MINERAL CONTENT AND STRUCTURE WITH PHYSICAL PROPERTIES. Continuing the discussion of igneous rocks, we find the texture and size of the crystals have an important bearing upon the resistance to wear. All other factors being equal, a coarse grained rock will give a higher percentage of wear than a fine grained rock. This is as would be expected from a petrographic standpoint, and can be explained largely from the standpoint of cleavage. Since in all the igneous rocks a large proportion of its minerals or crystals have easy directions of breaking, if the crystal be large a much larger volume of the rock will be involved in the break than if the crystal be small. We find then, as we would expect, that a coarse grained granite will give a greater percentage of wear than a fine grained granite, and a coarse grained Pl,aTE 3. — Section through basalt “boulder of weathering,” showing weathered effect close to the surface, hard fresh rock in the center. gabbro will give a higher percentage of wear than a fine grained diabase. A gain, we found in the description of some of the important minerals of igneous rocks that the feldspars have one of its cleavage directions about at right angles to the long direction of its crystal while in the case of hornblende and pyroxene their cleavages are parallel to the long direction of the crystal. A simple illustration will make the point clear. Consider two heaps of w r ooden blocks all of the same dimensions and being two or three times as long as their width and thickness. The first heap are all sawed so that the grain of the wood is at right angles to the long direction of the block while the second heap are all sawed 13 so that the grain is parallel to the long direction. Now cement each heap together with some strong cementing substance so that its respective blocks will be mutually interlocking in every conceivable direction. It is very evident that if we compare our two “made to order” rocks either from the standpoint of abrasion or from impact that “crossgramite” will be much inferior in wearing qualities to “straight graimte”. Applying this principle then to our igneous rocks of equal size grain, whether coarse or fine, we would expect to find that the basic igneous rocks which have a higher percentage of hornblende and pyroxene and less feldspars would hold together and withstand abrasion better than the acid igneous rocks, which have a higher percentage of feldspar and are low in pyroxene and hornblende. Also, that the acid rocks would be more brittle and friable and less desirable for road material than the basic rocks. This is as we find it and is probably the most logical reason why coarse grained gabbros and diorites give better results than the granites or syenites with the same size srystals. The same reasoning would apply in comparing the rhyolites or trachytes with the basalts. In order to further illustrate this principle of cleavage of minerals in its effect upon the durability of road materials let us consider a certain special type of granite which is called “graphic granite”. This rock is without doubt the most brittle and friable of all unaltered igneous rocks, and the most skeptical will be convinced upon careful observation that its brittle and crumbly nature is very largely due to the arrangement of its crystals, and the cleavage of the feldspar which composes probably two-thirds or three-fourths of its mass. By referring to Fig. 1 the leader will see that this rock has a peculiar structure in that it is made up almost entirely of two minerals, feldspar and quartz, and that the crystals of quartz and feldspar are very long and narrow, as well as parallel to each other. A further peculiarity of the structure of the rock is that the feldspar crystals are very large, in fact the specimen illustrated in Fig. 1 is only a part of a large crystal of feldspar enclosing within its mass a large number of smaller quartz crystals. It also happens that the two cleavage directions of the feldspar crystal at right angles to each other are both parallel to these long, slim, quartz crystals enclosed in the feldspar. This being the case these easy break ing planes pass between the quartz crystals and the rock naturally breaks between the quartz masses for long distances, scarcely rupturing them at all. For this reason a large mass of graphic granite can be easily broken with a tack hammer while the mass of ordinary granite composed of the same minerals in equal amounts, but whose crystals are interlocked in every conceivable direction would be very lard to break even with a 4-pound hammer. In comparing the different types of igneous rocks as to their adapta- bility for road material, we have already found that in general the fine grained rocks are superior to the course grained in wearing qualities. From this standpoint the rhyolites, trachytes, andesites and basalts 14 would be superior to their coarse grained equivalents, granites, syenites, tiiorites and gabbros. Again from the standpoint of mineral content we have found that rocks which contain a large amount of the tough minerals, hornblende or pyroxene, at the expense of the more brittle and friable feldspars are superior in toughness and wearing qualities. For this reason we find the diabases and basalts will, in general, give better results than the equally fine grained rhyolites and trachytes. The former are rich in hornblende and pyroxene with a comparatively small amount of feldspar, while the latter have a very large percentage of feldspars and a small percentage of pyroxene and hornblende. For this same reason granites and syenites which are made up of a high percentage of feldspars will be found inferior in general to the equally coarse grained diorites and gabbros whose mineral constituents are made up of a higher percentage of pyroxene and hornblende. By reference to the accompanying table which was compiled from a table in Bulletin No. 31 Office of Public Roads, U. S. Department of Agriculture, page 14, these principles are further illustrated: Table Showing Corelation of Mineral Content with the Physical Properties of Igneous Rocks. ROCK VARIETIES Mineral £> d p •-j N* Compositi percem :ide whose natural color is light brown or red. A large number of the red hills in the Willamette Valley have their soils painted red by the iron oxide which was derived from the weathering of the basalts and diabases which may be found practically unaltered only a few feet below the surface. All igneous rock masses are fissured or broken up into angular blocks, varying in size from a number of feet in length, breath and thickness to small sizes only a few inches in each dimension. These cracks or fissures make easy roads for the water to begin its work of rock weathering and as the work of decay proceeds each block, whether large or small, becomes separated from its neighbor by a space of varying thickness of softer weathered material between. Before these blocks have entirely disappeared we find them on the surface as rounded masses or “niggerheads”. They are called by the geologist “boulders of weathering”. These masses are often entirely unaltered only a few inches from the surface. Fig. 2 shows a group of these. Fig. 3 gives some idea of the weathered effect close to the surface. In some cases the iron oxide on the surface of these boulders become leached out by 19 the action of the rain, and as a reouit the old basalt boulder becomes almost white on the surface. The white minerals are secondary minerals such as kaolin, serpentine and talc. There are a number of localities in the Willamette Valley where these light colored boulders outcrop. Should a person suggest that these boulders were really basalt and that the fresh material could be opened up only a few feet below the surface he would in most cases be ridiculed. Some authorities claim that rock weathering is a factor to be considered in the durability of macadam roads. The claim has been made that such minerals as the feldspars will break down from the standpoint of decay and thus materially affect the rocks’ durability. This is not in accordance with the facts and the writer doubts if the weathering factor, from a purely chemical standpoint, is of sufficient importance to warrant consideration in a road material discussion. The weathering or decay of the ordinary rock making minerals is so extremely slow as to be scarcely noticeable in the period of years involved in the life of an ordinary macadam road. It is true that such minerals as feldspars, calcite and dolomite grind up easily under traffic but the reason as has already been given is on account of their friable or crumbly nature due largely to their cleavage. It must not be understood in this connection that a weathered rotten rock would be an economical road material. The discussion has entirely to do with the decay of fresh material after it has been placed upon the road. Before dismissing this discussion, however, it should be stated that for macadam work a small amount of v eathered material if used cautiously is not a detriment, but a positive advantage, owing to the increased amount of screenings produced and therefore aiding in the binding effect. We have already found that these secondary minerals formed by weathering are of a crumbly or friable nature. During the process of crushing these soft minerals crumble more readily than the fresh ones and thus produce a larger amount of fines or screenings. These are found to be excellent as a binder in macadam roads. Limestone has long been considered as an excellent material for a binder for harder rocks which lack binding qualities. Its peculiar qualifications in this regard can be best explained for the same reason, namely, that it produces a larger amount of extra fine screenings for binder. This is a vital point in the economics of road construction because few rocks produce sufficient screenings in proportion to the coarser grades, to bind them properly. DESCRIPTION OF LABORATORY TESTS. The most important properties of rocks by virtue of which they are adapted for road materials as discussed in most modern treatises on the subject of road construction are hardness, toughness, and cementing or binding qualities of the dust, and finer particles of the rock. The laboratory tests for approximating these properties as usually made in the laboratory are as follows: (Bulletin No. 31, Office of Public Roads, page 23.) Pirate 5. — Basalt quarry on Skinner Butte, Lane county. Columnar jointing due to contraction in process of cooling. 21 “Percentage of wear represents the amount of material under 0.16 cm, in diameter lost by abrasion from a weighed quanity of rock fragments of definite size. It is determined in the following manner: The rock sample is broken into pieces that will pass through a 2.4 in. ring but not through a 1.2 in. ring, and after being thoroughly cleansed, dried and cooled, 5 kgs. are weighed and placed in a cast iron cylinder (34 cm. deep by 20 cm. in diameter) closed at one end and having a tight-fitting iron cover at the other. This cylinder is one of four attached to a shaft so that the axis of each is inclined at an angle of 30 degrees with that of the shaft. These cylinders are revolved for five hours at the rate of 2,000 revolutions per hour during which the stone fragments are thrown from one end of the cylinder to the other twice in each revolution. At the end of the five hours the machine is stopped, the cylinder opened and their contents poured into a basin, in which every stone is carefully washed to remove any adherent detritus. This abraded material is then thoroughly dried, and from the amount lost below 0.16 cm, the percent of wear is estimated. Hardness is the resistance which a material offers to the displacement of its particles by friction, and varies inversely as the loss in weight by grinding with a standard abrasive agent. The test is made in the follow- ing manner: The test piece in the form of a cylinder about three inches in length by one inch in diameter is prepared by an annular core drill and placed in the grinding machine in such a manner that the base of the cylinder rests on the upper surface of a circular grinding disk of cast iron, which is rotated in a horizontal plane by a crank movement. The specimen is weighed so as to exert a pressure of 250 grams per square centimeter against the disk, which is fed from a funnel with sand of about 1 Vz mm, in diameter. After 1,000 revolutions the loss in weight of the sample, is determined and the coefficient of wear obtained by deducting one-third of this loss from 20. Toughness as here understood is the power possessed by a material to resist fracture by impact. The test piece is a cylindrical rock core similar to that used in determining hardness, and the test is made with an impact machine constructed on the principle of a pile driver. The blow is delivered by a hammer weighing two kg. which is raised by a sprocket chain and released automatically by a concentric electromagnet. The test consists of a 1 cm, fall of the hammer for the first blow and an increased fall of 1 cm. for each succeeding blow until failure of the test piece occurs. The number of blows required to cause this failure represents the toughness. The cementing value or binding power of a road material is the property possessed by a rock dust to act as a cement on the coarser fragments comprising crushed stone or gravel roads. This property is a very important one and is determined approximately as follows: One kg. of the rock to be tested is broken sufficiently small to pass through a 6 mm. but not a 1 mm. screen. It is then moistened with a sufficient amount of water and placed in an iron ball mill containing 22 two chilled iron halls weighing 25 pounds each and revolved at the rate of 2,000 revolutions per hour for two hours and a half or until all the material has been reduced to a thick dough, the particles of which are not above 0.25 mm. in diameter. About 25 grams of this dough is then placed in a cylindrical metal die, 25 mm. in diameter, and by means of a specially designed hydraulic press, known as a briquette machine is subjected to a momentary pressure of 100 kg. per square centimeter. Five of the resultant briquettes, measuring exactly 25 mm. in height are taken out and allowed to dry for 12 hours in air and 12 hours in a hot oven at 100 degrees C. After cooling in a desiccator they are tested by impact in a machine especially constructed for the purpose. This machine is somewhat similar to that used in determining the toughness and the blow is about the same, excepting that it is given by a 1 kg. hammer and the distance of drop does not exceed 10 cm. The standard fall of the hammer for a test is 1 cm. and the average number of blows required to destroy the bond of cementation in the five briquettes determines the cementing value. The specific gravity is the weight of the material compared with that of an equal volume of water, and is obtained by dividing the weight in air of a rock fragment by the difference of its weight in air and water. Given the specific gravity, the weight per cubic foot of a rock is found by multiplying this value by 62.5 pounds, the weight of a cubic foot of water. DISCUSSION OF THE YALUE OF LABORATORY TESTS. The abrasion test for giving the percentage of wear as described above is one of the most useful of laboratory tests. It gives the practical road builder some very useful information in that it measures approximately the property of a rock to withstand the grinding action of severe traffic. The test is of value only in so far as the conditions are duplicated but it seems probable that the results in the two cases would be fairly proportional. The laboratory test for hardness is of no great importance, since it fails to give any information which is not given by the test for abrasion. These two tests agree so closely that the labor involved in making this test is not warranted from a practical standpoint. Toughness as measured in the laboratory is closely related to the percent of wear, as the results in most cases approximately agree. As would be expected a tough rock will give a low percentage of wear. The main difficulty with this test is to secure a sample for a test piece which will represent the average condition in the rock being tested. This difficulty arises for a number of reasons: the test piece often contains an incipent fracture which causes the piece to give way under the ham- mer along this plane of weakness and as a result the variation is great. Again in foliated rocks the result means very little because if hammered at right angles to the plane of foliation the result would obviously be very different from that if hammered parallel to this plane. It is evident 23 from this that the general results from the impact test must give a wide range of variation. The test for absorption of water is not so important in the Willamette Valley as it would be in regions of colder climate. The destructive effect of frost as measured by this test would be almost negligible in this climate. The specific gravity of the great majority of rocks used for roai material is fairly constant, occuring usually between the limits of 2.65 to 3.60. As a qualification for road materials the heavier rocks such as basic igneous ones, will be somewhat superior to the lighter weight rocks The specific gravity would also be useful in determining the weight of a large amount of rocks and would be convenient in computing freight rates. CEMENTING OR BINDING VALUE OF ROCKS IN MACADAM ROADS. Most authorities on road construction claim that rock powder or dust when wet has a tendency to set or recrystallize, and by virtue of this setting quality it binds its particles together much the same as lime hardening in mortar produces a bond between its particles. It is also claimed that some rocks are so absolutely void of this property that it is impossible to compact them either with a road roller or under traffic. With these claims we are forced to take issue, largely because they are not substantiated by the results obtained in practical road making. In the first place, it has been proved in a large number of cases over the country that such rock as quartzites and cherts which have a minimum cementing value according to the usual test, make some of the best macadam material. A large number of our best basalts in the Willamette Valley have very poor cementing values if considered from the stand- point of the laboratory test, and yet there is no difficulty in binding these materials in macadam roads. In fact, in a number of cases these basalts have been used in the valley for a number of years and have given excellent results. It is found that a little “dirty sand” or gravel screen- ings is all that is necessary for a binding material where there is a lack of rock screenings to fill the voids. This effect of binding the rock fragments and particles together in i\ macadam road can best be considered from two separate and distinct causes; first, the mutual interwedging effect of contiguous rock particles when compacted as much as possible, and, second, the binding effect caused tv the ca illary action of water. This wedging effect is best illus- trated by noting the fact that in the process of construction of any macadam read the surface after No. 1 and No. 2 have been laid and rolled, before the screenings have been put on, will sustain a load if care- fully applied, nearly equal to that of the finished macadam. This result is obtained almost entirely on account of this wedging effect and because of this a heavy load applied on a small area on such a surface in being transmitted down through six inches of crushed tightly wedged rock, will be distributed over an area on the surface of the subgrade many PivATE 6. — U. S. object lesson road near Fair Grounds, Marion County. Note the fact that there is no main traveled track on any part of the surfaced road, due largely to the low crown. 25 times as large. Thus we see that a macadam road is able to support its load almost entirely by virtue of its interwedging effect between its an- gular rock fragments. However, this does not sufficiently hold each r ock fragment in its wedged position, because the surface particles can easily be displaced. This is the peculiar office of the finer rock dust and water, as will be seen below. The cementing test as is usually carried out gives very little practical information for the use of the road builder, because there seems to be very little in common between the conditions which obtain in the macadam road with that in the laboratory. In the completed macadam road the tiny capillary pore spaces are nearly or quite filled with water while in the labarotary the water in these capillary spaces is supposed to be all baked out. It seems to the writer that this is a very vital point and one that makes the laboratory test for cementing value worthless. It would be reasonable to conclude that oridinary clay has as high a cementing value as the best rock dust, if this test is accepted as con- clusive. It is only necessary to mix the clay with water until it is made into a thick dough. “About 25 grams of this dough is then placed in a cylindrical metal die and by means of a specially designed hydraulic press known as a briquette machine is subjected to momentary pressure of 100 kilograms per square centimeter. Five of the resultant briquettes measuring exactly 25 millimeters in height are taken out and allowed to dry twelve hours in air and twelve hours at 100 degrees C. After cooling in a desiccator they are tested by impact in a machine especially con- structed for the purpose. The standard fall of the hammer is one centimeter and the average number of blows required to destroy the bond of cementation in the five briquettes determines the cementing value.” Under this treatment the clay gives a higher test for cementing value than the best rock dust, while the facts are, clay has no cementing value because when wetted it immediately becomes soft and plastic. Without question it is the action of surface tension of water in these capillary spaces between the tiny particles that is a most important and vital factor in the binding material of a macadam road. In order to prove the importance of water in the binding material of a road it is only necessary to note the fact that our dry Oregon summers are the worst enemy to macadam roads that we have. See Fig. 4. A great number of our macadam roads begin to ravel during the long dry sum- mer but immediately become firm and hard when the rains resume in the fall. Again any practical road builder in the country will attest to the fact that the easiest macadam roads to keep in repair are those which are situated in heavy timber, thus shutting out the sun. Under these conditions the tiny capillary tubes reach the very surface of the road and thus hold or knit each tiniest particle to its neighbor. If it were possible to make a microscopic examination of a section of a well made macadam road it would be found that the voids between the largest pieces of rock would' be filled with smaller pieces of rock, and the voids between these smaller pieces would again be filled by much 1^4 26 smaller pieces and so on until the finest particles filling the very tinest voids would be microscopic in size. Under this arrangement the condi- tions for capillarity would be as complete as in the finest clay. Our microscope would show that each particle of rock or dust was completely surrounded by a tiny film of water, or in other words that the whole mass was completely ramified by an intricate network of tiny capillary tubes, which tend to bind the mass together like so many threads. The strength of this water bond lies in the fact that these tubes are so tiny that water passes through them very slowly even if under great pressure and if any physical force would tend to move any single particle in any direction it is evident that it could not move without moving the water in the capillary tubes in that neighborhood. Now since it requires a great force to move water rapidly in these tiny capillary tubes the resistance to the movement of the aforesaid particle would be very great. This principle is the keynote in the theory of the binding action in a macadam road. This is the obvious reason why the practical road builder finds that clean sand is a very poor binding material while bank sand which contained a considerable amount of dirt or silt is one of the best materials he can get. This is caused by the fact that the dirty sand has a sufficient amount of the finer particles to fill the voids between the coarser sand grains, while these finer particles have their voids again filled by smaller particles and so on and thus the conditions for more perfect capillarity are fulfilled. In case the clean sand is used as a binder the voids between these coarse grains are comparatively large, the capillarity being thus very greatly diminished. The strength of capillarity measured by the height of rise in a tube above its hydrostatic level, is inversely proportional to the diameter of the tube, that is to say reducing the diameter of the tube to one-half doubles the heighth that water may be raised in the tube, by capillarity, or reducing the diameter to 1-100 enables the water to rise 100 times as high. In order that the above discussion may not prove misleading a few words of caution will not be out of place. Some might infer that since a little dirt or silt is very beneficial in binding material for a macadam road, that more would be better and thus lead to a promiscuous use of clay as a binder. This would be an unfortunate mistake and one that is often made by the road builder. By referring once more to our microscopic section through a macadam road it is evident that if we have present a greater amount of particles of a certain size class than is required to fill the voids of the next coarser class the tendency will be to destroy the wedging effect between the pieces or particles of said coarser class. It is evident that the amount of fine clay particles which would be required to fill the voids between the next coarser particles would be a very small percent of the total volume of the macadam material. It is of the utmost importance that a field examination be made in connection with the laboratory test. Unless this is done exhaustive laboratory tests will often be made upon very inferior material when 27 excellent material is at Land, in otner words, it requires as much skill to take the sample as it does to determine the fitness of the material. Very often a sample of weathered rock of inferior quality is sent in to the laboratory while excellent road material in the fresh rock would have been found only a few feet beneath the surface. An example by way of illustration will suffice. The writer has in mind a particular hill in the Willamette Valley from which a sample had been taken some time since and sent to the Department of Public Roads, Washington, D. C. Their report was unfavorable and in the case of the sample sent in was entirely correct. On account of this authoritative test the whole hill was abandoned by the road builders. The fact is, however, that there is a large and favorably located outcrop of excellent road material on that same hill not more than 100 feet from where the above sample was taken, it being a different formation and an entirely different type of rock. ROAD MATERIAL SITUATION BY COUNTIES. BENTON COUNTY. Benton County’s rocks include a considerable amount of hard igneous material as well as some of the softer sandstones and shales which are not well adapted for road purposes. The exposed outcrops are found entirely in the foothills and a few buttes scattered over the floor of the valley. The igneous rocks are fairly well distributed through different parts of the county. In the extreme southern end of the county are numerous outcrops of a good hard basalt. The hills two miles southwest of Monroe are made up of this material. A few outcrops are found near the county line one and one-half miles south of Monroe, but in this section, are covered with considerable depth of soil. By prospecting good quarry sites should easily be obtained. A number of good outcrops are also available two miles west and one south of Monroe in the vicinity of the old Belknap place. These rocks give excellent tests for road material. The hills immediately west and northwest of Monroe are sandstone which crumbles very readily under abrasion and are entirely unfit for road material. Spring Hill one and one-half mile north and one-half mile west of Monroe on the south side of the C. & A. railroad, is made up of a good quality of basalt. An excellent quarry could be located on the north side of the hill at this point. It is a particularly desirable location for a site because of the transportation facilities. In the neigh- borhood of Bellfountain are a few outcrops. Near the summit on the southwest slope of the Butte just east of Bellfountain a medium size grained diabase is found, but no outcrops were found at the base of the hill. An outcrop of basalt which gives excellent tests for road material is found two and one-half miles northwest of Bellfountain in the canyon of Rees creek just above the N. R. Stauturf place. This is an excellent site for a quarry because situated well above the road, and would require little or no stripping. About one mile southwest of Pirate; 7. — Kwald quarry near Salem showing extreme fissured condition of basalt. 29 Bellfountain are also some basalt outcrops and by prospecting a good site for a quarry could probably be found. On the J. H. Edwards place one and one-half mile northeast of Bellfountain quite an extensive out- crop of a good hard diorite is found. This material will make a good road metal, although it is not so good as basalt. The southwest slope of the hill will be a convenient site to accommodate a considerable area, since no other available outcrops are near. The hills for four or five miles north of Bellfountain are sandstone which is unfit for road materials, and probably very few if any outcrops of a good road rock can be found in this section. On the Park place six miles south of Philomath a small intrusion of basalt in sandstone is found. This material is of fair quality for road material but the quarry is not in a favorable site for the economic handling of the rock. It is probable that more favorably situated outcrops could be found in this vicinity. The quarry one-fourth of a mile south of the Park quarry is a semi-consolidated sandstone and would be entirely unfit for road material. Erwin Butte ten miles south of Corvallis on the Monroe road is almost entirely sandstone on the surface. Doubtless the main mass of the hill is basalt, and although but one point is found where the basalt is exposed a little prospecting would probable locate a good igneous rock quarry on this hill. On the south slope of the butte on the Jesse Foster place, about two and one- half miles southwest from Erwin Butte a hard dense basalt outcrop is found which is excellent for road materials. On the north side of the hill southwest of Philomath is found an outcrop of fine grained syenite. This rock like the above mentioned diorite does not give as good results for road materials as the more basic denser basalts. It is a good rock however and will wear well under any ordinary traffic. Some of the streets of Philomath have been macadamized with this rock with good results. The southwest side of the same hill seems to be made up of sandstone which should be avoided in searching for road rock. One mile farther south on Hartless Hill at the J. H. Melville place there is found an outcrop of very much altered basalt. This is soft and easy to quarry but the material thus far obtained will not make an economical road material. It grinds up readily under traffic and makes a smooth road quickly, but will not wear well enough to warrant the expense of putting it on the road. Such weathered rotten basalt is no better than soft sandstone for road material. An effort should be made under these conditions to find points where fresh basalt can be obtained with minimum amount of stripping. (See selection of Quarry Sites.) West and north of Philomath are found a large number of outcrops of excellent hard trap rocks. West from Philomath in the vicinity of the railroad leading to Noon Bros, sawmill are numerous outcrops of a granular rock called diabase which is good material. A quarry of fresh hard basalt is opened up about one and one-half miles south from Wren just south of the summit of the hill. On the C. & E. railroad between Philomath and Wren are several outcrops of 30 basalt rock exposed in the railroad cuts. Some of these exposures show good, hard, dense material and will make excellent quarry sites. On the wagon road leading to Blodgett following the railroad many good basalt exposures are found, sufficient both in quality and quantity to supply this neighborhood with excellent road material. One and one- half miles from Wren on the road leading northwest toward Kings Valley is found a basalt quarry. Some of the rock in this quarry is excellent and hard while part is quite soft. By intelligent selection the material in this quarry can be used to good advantage. Three miles west of Corvallis on the road to Wren are outcrops of diabase of medium size grain which is good rock for macadam and from this point to Wren are several good exposures of basalt. Northwest of Corvallis one and one-half miles are found a few quarries exposing the igneous rock, syenite. This is a good rock for road material and although somewhat inferior to good fresh dense basalt will give very satisfactory results as a road material. The hills north of Corvallis on west side of Southern Pacific railroad are very largely basalt. A number of outcrops have been opened up as quarries but in no case was there found fresh unaltered rock. In these quarries such as Hahn’s one and one-half miles northwest from Corvallis near Vine- yard hill, the Bauer quarry near Mountain View school house and Walter Wiles quarry near the north county line, the rock is so much weathered and rotten as to be entirely unfit as a road material. In a number of communities where the practice is to haul rock on the road without crushing or rolling these rotten rocks are quite popular. These rocks make a passable road in the winter because they grind up readily and make a firm enough surface to support the ordinary load. These roads will not give sufficient wear however, to warrant the expense of putting this material on the roads, when only a little additional expense in crushing and rolling a hard rock would produce an excellent macadam road that will last for years. Some prospecting should be done in these sections to find if possible, points where the fresh rock could be opened up with minimum amount of stripping of soil or overburden. On the George Lindeman place for example it is probable that a good hard rock quarry could be opened up with little difficulty. East of the Southern Pacific Railroad and north of the Willamette river the outcrops are sandstone and probably no good road material can be found in this area. For considerable areas in Benton County especially south of Corvallis, the Willamette river gravels will be the most available and economical materials that can be had. If the coarser gravels are selected and crushed, they will give excellent results. CLACKAMAS COUNTY. Clackamas County is well supplied with excellent material for road building as well as being well distributed over the county. The outcrops in this county are almost entirely basalt which might be divided into two classes owing to their difference in appearance. The dark brown or 31 . black, dense, very fine grained basalt, and the gray basalts which are somewhat more coarsely crystalline, although being still very fine grained rock. These gray basalts are somewhat more porous than the dark and although they are all good rocks for macadam purposes the dark colored more dense basalts will give the best wear under heavy traffic. These lighter colored basalts have a higher percentage of feldspar and a lower percent of pyroxene than the dark colored ones. As com- pared with these we find the dark colored basalts having less amount of feldspars in proportion to the pyroxene as well as having considerable amount of rock glass present. These gray or light colored basalts are very similar to those found in Multnomah County on Rocky Butte, Kelly Butte and west of Council Crest. We find them outcropping along the Clackamas river in the neigh- borhood of Baker’s bridge some seven miles east from Oregon City. They are found outcropping on both sides of the river canyon from Baker’s bridge some three or four miles east. We find them exposed again in large quantities on both bluffs of Clear Creek, west of Logan. From this point to Viola they are found outcropping more or less all along the creek bluffs. It has already been mentioned in the discussion of rock weathering how these basalts change in color to reddish or brownish boulders upon the surface. These are found scattered all over the hills in this section and are due to the decay of the rock found just below the soil. There are numerous hill sides on the Aberneathy road showing outcrops of these rounded boulders and in favorable areas the rock could be easily found in place in these sections with comparatively small amount of stripping. Still farther south, we find these same light colored basalts in the neighborhood of Beaver Creek. There are numerous areas in this section where the erosions of small streams have laid bare the rocks beneath making favorable points for quarry sites. Considerable work is being done in road building in this section as well as farther south along the Molalla road one half mile north from Mulino at a cut in the hill which slopes to the south is an excellent site for a quarry. The high bluffs on the west side of the road are all composed of an excellent fine grained hard basalt somewhat darker in color than the ones in the neighborhood of Beaver Creek just mentioned. This is a good quarry site, first because it is favorably situated near the road and also because little or no stripping would be required. At a point about four miles east of the town of Molalla on the east side of the river are found outcrops of a good hard basalt and from this point to Mulino along the stream bluffs occur a number of outcrops of the same materal. It is found again still farther south of Molalla in the Wilhoit country. Considerable area in this section contain outcrops of good dense basalt and if favorable localities are selected good quarry sites can be obtained with small amount of stripping. In the neighbor- hood of Glad Tidings on Rock Creek are found a few outcrops of impure limestone. This rock cannot be recommended as an excellent road Plate 8. — Kwald quarry, Marion county. 33 material if used by itself it being somewhat soft and friable and easily grounded up under traffic. Such rock if used alone makes macadam roads very quickly and gives excellent results at first but are not adapted for heavy traffic. Along the banks of the Molalla river close to the water’s edge will be found outcrops of sandstone and shales. These rocks are not at all adapted for road making purposes being easily ground up under traffic and should be shunned by the road builder in searching for material. Along the bluffs of the Willamette river on either side from New Era to Oregon City are found high bluffs of basalt, 50 to 100 feet high standing almost vertically. This large mass of rock is almost entirely of a dark fine grained dense variety of basalt before mentioned. A number of excellent quarry sites could be selected in this locality on account of the convenience of transportation being accessable either to railway or water transportation on the river. Farther north we find these same dark basalts outcropping on the Clackamas river near Park Place, as well as in the hills east from Clackamas station. Numerous basalt outcrops are also found farther down the Willamette river toward Portland. In the neighborhood of Oswego these outcrops are especially prevalent. In this section care needs to be exercised in selecting the more dense portion, the mass here being made up of layers of cellular basalt interspersed with the more dense varities of basalt. This has already been explained as coming from the fact that gases escaping dur- ing the cooling makes the lava sometimes very porous or sort of lava froth. This porous lava from the standpoint of macadam materials should be shunned as far as possible because it lacks considerably in wearing qualities as compared with the more dense varieties. These outcrops of basalt are found in abundance for two miles to the southwest towards Stafford. In the neighborhood of Stafford are no very important outcrops for the reason that they are largely covered too deep with soil. LANE COUNTY. Lane County is well supplied with the hard dense basic igneous rocks. With the exception of a few stray buttes situated here and there on the floor of the main valley, these rocks are confined entirely to the foot- hills bordering the valley proper. These basic rocks are all dense hard basalt or fine grained diabase and without exception give excellent tests as road metal. The hills south from Eugene from the Bailey school east to Judkins Point are all basalt and have numerous points which would make favorable quarry sites. At Judkins Point just above the Southern Pacific Railway is exposed an outcrop of excellent hard olivene basalt while just below near the road is a soft sedimentary rock which is not fit for road material. The Butte just south of Springfield is basalt and considerable of this material has been used on the roads in the vicinity with good results. Skinner’s Butte is a porphyritic basalt being made up largely of feldspar and pyroxene. This is one of the most perfect ex- amples of columnar jointing to be found anywhere in the valley. See 84 Fig. 5. This is an excellent road material. The Rossman Quarry two °nd one-half miles northwest from Eugene is a fine grained diabase, has excellent qualities as a road material. This quarry furnished the material for building the Santa Clara road. An outcrop of basalt of small area is found on a low hill one mile west from Eugene just east of the road. In the vicinity of Oak Hill school the hills for two miles both east and west are sandstones of poor quality for road materials. Rattle Snake butte farther to the northwest is again basalt of excellent quality. A few good outcrops are found still farther north along the foothills Dut no detailed examination was made except in the very northern part of the county. About two miles northeast from Springfield where the railroad first touches the hills are found an abundance of basalt out- crops. Here are some excellent sites for quarries both from the stand- point of their proximity to railroad transportation as well as requiring little or no stripping. Numerous outcrops of the same material are found all along the railway from this point to Wendling. The hills just east of the McKenzie river from Coburg to the southeast for several miles have numerous outcrops of the same hard basalt. At a point in the hills near the McKenzie river bridge two miles southeast from Coburg is an excellent quarry site, largely on account of its situation on railroad and wagon road, making a good distribution point for either quarry rock or gravels. North from Coburg the first foothills contain a number of basalt outcrops, the most available being a butte one and one-half miles north from Coburg, Rockhill three mills north and West Point Hill on the Lane-Linn county line. In the southern part of Lane county in the vicinity of Cottage Grove the trap rocks are well distributed. The hills immediately on the northwest side of the town of Cottage Grove extending southwest past the cemetery to the town of Latham contain only outcrops of a volcanic conglomerate or tuff. This rock is not sufficiently consolidated to make a good road material. Beyond Latham, however, on the west side of the valley the hills are basalt, there being numerous excellent outcrops from this point to beyond the Divide. On the east side of the valley for a distance of six miles south from the town of Cottage Grove the hills are all basalt. A few good outcrops are found on the terrace just southeast of the town. The quarry from which the material was obtained for paving the city streets in Cottage Grove is about one and one-half miles north from the city. The mass is excellent columnar basalt and gives good results. From this point north to Cresswell the valley is comparatively narrow and the hills almost entirely trap rocks. Lane County is fortunate as well as some of the neighboring counties in having a large amount of excellent gravels in the river beds which when crushed make excellent road materials. These gravels are well dis- tributed through the central part of the valley and will accommodate a large area which is situated at prohibitive distances from available deposits in the foothills on either side of the valley. 35 LINN COUNTY. Linn County is also very fortunate in having a goodly supply of trap rocks which are well distributed. A glance at the map will show a more or less continuous line of outcrops extending from the vicinity of Kings- ton on the north Santiam river through the county in the vicinity of Lebanon and Brownsville to the Lane county line. This line marks rough- ly the first foothills on the east of the main floor of the Willamette Val- ley. This leaves an area west from this line to the Willamette river of ap- proximately four hundred square miles in which no outcrops or rocks are found except a few stray buttes. It is evident then since this area averages about ten miles in width by utilizing the gravels in the Willamette river the maximum haul need not be more than about five to seven miles. This is a far better distribution of road materials than is usually found in areas of equal size. Along the Santiam river from Kingston to Lyons is an almost un- limited mass of dense black basalt. The Santiam river has cut its way through this mass exposing a bluff on the south side of the river rising from 50 to 150 feet high. Although this material is considerably weathered on the surface in places the mass as a whole is excellent material and is one of the best quarry sites in the Willamette Valley for getting out a large quantity of rock. Situated upon the C. & E. Railroad makes it a good distribution point. This basalt formation is immediately underlaid by sandstones and shales which are very inferior material for road metal. This same basalt outcrops over a wide area to the south of the Santiam in the vicinity of Kipsharts Bluff as far as the town of Jordan. Good quarries could be opened up almost anywhere in this area. The Mespelt quarry situated about two and one-half miles southeast froxr Thomas shows a good face of basalt typical of a number of out- crops found in this neighborhood. It is very hard, black, dense and unaltered and as good rock for road material as can be found anywhere. Peterson’s Butte three miles southwest from Thomas, has some good outcrops of basalt which will make good road material and some excellent quarry sites could easily be located. The southwest slope of this butte will be found the most favorable because the soil is thinner and requires less stripping as has been noted before in the description of the general geology of the valley. On the west slopes of Kees Butte one-half mile east of the town of Lebanon is an excellent quarry of fresh, hard black basalt exhibiting a very fine columnar structure. This material is very similar to the rock in the Mespelt quarry, giving excellent tests as a road material. This is a very favorable site for a quarry being near the railroad and about 100 feet above the wagon road. An almost unlimited amount of material could be obtained and easily handled. About two and one-half miles northeast of Kees Butte some excellent outcrops of basalt are found. Between this point and Kees Butte, however, is a considerable Pirate 9. — Basalt cliffs along the Columbia River, Multnomah County 37 area covered with sandstone. This rock in common with nearly all of our Pacific Coast sandstones, is not sufficiently consolidated to make good material for road construction. If used upon the road it would soon grind to powder. Ward’s Butte situated about one and one-half miles southwest of Plainview and Saddle Butte three miles east of Shedd are solid masses of basalt. This rock is almost identical with that of Kees Butte. A number of good quarry sites could be located upon each of these Buttes, the southwest slope again being more favorable. The rock in Saddle Butte three miles east from Shedd is finely fissured, similar to the Ewald quarry in Marion county, south of Salem, and on this account would be easily handled in quarring and crushing. The quantity of basalt in either of these Buttes is practically unlimited and the material as good as the best. About two and one-half miles north of Brownsville some good outcrops of basalt are found and excellent quarry sites could be selected. On a butte situated two miles south of the town of Twin Buttes just east of the railroad track is another excellent quarry site. It is close to and above the railroad so the rock could be handled conveniently by railroad transportation. The material is the same hard, dense basalt exhibiting the columnar structure of the rock in Kees Butte. Undoubtedly similar outcrops would be found in the foothills from this point south of the county line but a detailed examination was not made in this section. MARION COUNTY. . .Marion County has a large amount of excellent rocks for road building purposes and they are fairly well distributed. The southwestern part of the county being the most fortunate in this respect. The area south from Salem and west of the Southern Pacific railroad probably has a better distribution of good hard, dense, black basalt than any other equal area in the Willamette Valley, there being very few square miles in this area in which a good quarry site could not be found. There have already been opened up twelve quarries in this area and samples taken from them show a remarkable uniformity in the type texture and quality of the rocks. These basalts are all very dense, hard, tough varieties, which from the laboratory test as well as practical service on the roads have proven excellent for road materials. On account of the uniformity in the quality of these materials it will not be necessary to discuss them separately. The most noted quarry in this area is the Ewald quarry, two and one-half miles south of Salem. The mass of rock is unique in one respect, namely on account of its being profusely fissured. Incipient fractures ramify the mass to such an extent one would have difficulty in finding a solid piece larger than a man’s head. On this account it aids materially in quarrying, doing away with the expense of sledging the material before being handled by the crusher. Fig. 7 shows the appearance of the rock in the face of the quarry giving some idea of 38 the fissured condition. Fig. 8 shows a general view of this quarry. This same material which is found in the Ewald quarry, outcrops on what is known as the Creek Canyon on the Cunningham place two miles southwest from the Ewald quarry. The same material is found three miles southwest from Salem outcropping on the river road. This would make an excellent site for a quarry. The Poyser quarry seven miles soutnwest from Salem and two miles northwest from Independence is an excellent quarry site on account of being so favorably situated with reference to transportation, being on the county road on the east bank of the Willamette river. The Lankford quarry is located four miles southwest from Salem on the Croisan Creek road, one and one-half miles up the creek from the river road. Numerous outcrops of the same material are found further south along the Crosian Creek Canyon, the Davidson quarry seven and one-half miles southwest from Salem being at the head of Croisan Creek about five miles east from Independence. The Gilbert quarry one-half mile west from Rosedale, is a good quarry site. The mass is well fissured and broken up. The Rosedale Quarry is located one and one-fourth miles south from Rosedale near the southeast corner of the R. C. Jory farm and one-half mile east of tue Kosedaie road. The Feeble Minded Institution quarry one and one-half miles east from the Davidson quarry is of the same dense, hard basalt. An exten- sive outcrop of basalt is found one-half mile northwest from Turner on the east side of the hill. This would be an excellent site to obtain a large quantity of rock as there would be very little stripping and a quarry face could soon be developed here 75 to 100 feet high. Numerous outcrops of similar material are found in the hills south from Turner to Marion. Also on east side of the Southern Pacific Railway from Turner north to the Asylum farm. In the vicinity of Silverton there are numerous outcrops of basalt. The hill just east of the town is made up of basalt obscured by a few feet of soil. Farther to the northeast from Silverton the hills are mostly basalt. The Morley quarry four miles northeast from Silverton is an excellent quarry site. In the neighborhood of Scotts Mills are found some excellent outcrops of basalt especially in the canyon of Butte Creek south from the town. These masses are as good as the best in quality, but will be somewhat harder to quarry on account of the lack of fracturing or fissuring which is found elsewhere. The Whitlock quarry one mile northwest from Scott’s Mills is very similar to the Morley quarry but is not so good a quarry site on account of being too near the creek level. The butte known as Mt. Angel is one huge mass of basalt. The Mt. Angel quarry is located on the southwest side of the butte well up toward the summit. The rock where the quarry is opened is the same profusely fissured basalt as before described in the Ewald quarry. The basalt in this butte varies considerably in its density. The outcrops in some portions being very porous. This is especially true farther toward the summit near Mt. Angel College. The writer would suggest 39 that a quarry just as good as the present road rock quarry could be opened up farther down the southwest slope of the hill and thus be more available from tne road as weii as save considerable time and expense climbing the hill to the present quarry. In the extreme north side of the county there are some excellent outcrops of basalt southwest from Butteville. On the old Mathoit place three-quarters of a mile southwest from Butteville is a prominent butte of basalt The north side of the butte slopes down to the Willamette river very steeply and exposes the basalt. This is an excellent site for a quarry as a large working face could be quickly and easily opened up. The material is hard, black basalt very similar to that found in the Tualatin hills across the Willamette river in Yamhill County in the vicinity of Newberg. Similar outcrops of basalt are found one-half mile farther southwest on the Tong Lee place. In northern Marion County there is an area of over 200 square miles between Mt. Angel and Silverton on the east, the Willamette river on the west and north, and Salem on the south in which there are found no available outcrops of road materials. The deposit of the Willamette river gravel on the west and north are available, however, and together with the outcrops already mentioned on the boundary of this area will supply it reasonably well. MULTNOMAH COUNTY. Multnomah county has a large amount of the fine grained basic igneous or trap rocks which are excellent materials for road building, however, these materials are not so well distributed over the county as in the case of some of the other Willamette Valley counties. The western part of the county is well supplied, and again we find plenty of road material in the eastern part of the county, but a large area in the central part, extending from Rocky and Kelly Buttes east to the Sandy river has no good road material except gravel. On the west bank of the Willamette river extending from Oswego to Multnomah’s north county line outcrops of basalt are found in all the canyons which cut the east slope of the highland. In some of these canyons extensive sections are exposed showing that this material has been deposited in a number of successive lava flows. These different outcrops are quite uniform in quality, being hard, black, dense basalt. The only exception being now and then a layer of cellular basalt, which being more or less porous, lacks in power to withstand abrasion. In some of these quarries the material shows considerable weathering in certain places in the quarry owing to the fact that under ground waters have penetrated deeper in these places. A limited amount of this weathered material for macadam purposes is no disadvantage, but as we have already noted, a positive advantage on occount of the additional binding power resulting therefrom due to the larger percentage of screenings produced. It is very seldom in any rock that sufficient screenings are produced to bind the coarser materials and from exper- 40 ience this weathered rock is found to he excellent as a binding material. Samples of rock taken from Linton quarry one and one-half miles east of Linton, Canyon quarry one-half mile north of Council Crest, Markham Gulch, Jackson Canyon just west of the City Park, Tanner’s Creek and Fulton’s quarry are very similar and give excellent tests for road materials. Three miles west of Portland on the Cornell road is a quarry of dense black basalt very similar to that found in above mentioned quarries. Council Crest quarry is located on the west slope of Council Crest. The rock found in this quarry is gray in color and somewhat more porous than the darker basalt. This rock is more nearly an andesite than a basalt and on account of its less dense nature gives a higher percentage of wear by abrasion. It is somewhat inferior to the Plate; io. — C ounty prisoners at work. Kelly Butte quarry, Multnomah county. black basalts as a road material but gives good wear. Some outcrops of this same andesite are found one mile west of Council Crest. This would make a good quarry site as there seems to be an almost unlimited amount of material. Pointer’s Butte one and one-half miles farther northwest is of the same material. Quarries might be opened here to accommodate areas in both Washington and Multnomah counties. Taylor’s Ferry quarry contains an excellent quality of dense, black basalt. On the east side of the Willamette river available outcrops of rock are found at Kelly’s Butte and Rocky Butte. The material in these buttes are somewhat similar, Kelly’s Butte being considerably finer grained. These rocks might be classified andesite also, but are some- 41 times known as gray basalts. The Rocky Butte rock is very similar to the outcrop west of Couiicil Crest as well as a number of outcrops in Northern Clackamas County near Baker’s Bridge and all through the Redland country. These rocks in quality are somewhat inferior to the best basalts but make good road materials. They are not as well adapted for heavy traffic as the dark, dense basalts. They are . considerably coarser grained, have smaller percent of the pyroxenes and are made somewhat porous to considerable depth by the weathering effect of under ground waters. The great depth to which the first stages of this weathering action takes place can be noted in the Kelly Butte quarry where at a depth of 40 to 50 feet below the surface the large fissure blocks show the gradation from the gray to the darker colored basalt, the dark being considerably harder than the gray. The Kelly Butte rock is good material however on account of its fine grained texture and withstands abrasion nearly as well as the black, dense varieties. Just east of the Sandy river at Troutdale is an exposure of gray basalt very similar to that found in Rocky Butte. This is an excellent quarry site as the material can be easily handled and transported by rail. From this point up the Columbia river there is a continuous ledge of basalt reaching through the county, showing an exposure very nearly vertical, and varying in height from 50 to 200 feet, see Fig. 9. A large part of this mass is excellent road material but is more available from the railroad at the foot of the bluff than from the highlands above. Very few outcrops of this basalt are found on these highlands because they are covered with a considerable depth of soil. About three miles east of Gage in the creek canyons a number of outcrops of basalt similar to the Rocky Butte material are exposed. These will doubtless furnish good quarry sites accommodating a large area in this section. POLK COUNTY. Polk County is not as well supplied with available outcrops of road material as are some of the other counties in the valley. However a number of good quarries have been opened and a number of outcrops located which will be of great service to the road builder. In the vicinity west from Dallas the hills contain some outcrops of basalt of excellent quality. The two quarries from which the rock for the city has been obtained, one three miles west and the other two miles west and one mile north, show very fine grained, black, dense varieties of basalt which are as good in quality as any to be found in the valley. Four and one-half miles north and one mile west of Dallas is another excellent basalt quarry. The mass of rock is profusely fissured similar to that found in the Ewald quarry near Salem and because of the fissures is more easily quarried than it would be otherwise. Four miles southwest of Dallas are located some limestone quarries which were recently purchased by the Oswego Cement Company of Portland. This rock seems to be very popular in this section as a road material, largely on account of the fact that it is easly quarried and 42 crushed and works down quickly into a good road without being rolled. From this standpoint it certainly is a good rock for road material but cannot be recommended for use alone for building the best macadam roads. Under heavy traffic the surface of the road will be found to wear rapidly and will need constant repair, as the rock is not hard enough to sufficiently withstand the abrasion of heavy traffic. This rock used as a binder for a harder trap rock would make excellent macadam roads, which would give the best of satisfaction. Just west of the town of Falls City is a quarry in coarse grained diabase. This is a tough, hard rock and gives good tests as a road material. Four miles southeast of Falls City is a quarry the rock being the same as that of the Falls City quarry. In the vicinity of Multnomah some basalt quarries could probably be opened up by making careful search as is evidenced by the fact that basalt boulders are found strewn over the hillsides in this vicinity. Polk County has large areas which apparently have no available road material. On this account it will be necessary to depend largely upon the Willamette river gravels for economic materials. By crushing and transporting by rail these gravels can be readily distributed to nearly all parts of the county. TILLAMOOK COUNTY. Although Tillamook County is not located in the Willamette Valley, it is included in this bulletin because of the great demand for investigation of the materials in this section. This county has done a great deal of work in building up to date roads and deserves credit for the result obtained. Tillamook County has a greater variety of rocks than any of the Willamette Valley counties and as might be expected their qualifications for road making are just as varied. About five miles southeast from Tillamook city near the Red Clover cheese factory on the Trask river is found an outcrop of rhyolite tuff which appears on the map as sand- stone. This material is formed by an accumulation of volcanic fragments more or less cemented together and on the whole makes rather poor macadam material. Aside from the fact that it is easily ground up under traffic it seems to slack on exposure to the weather and although it rolls down and makes a good, smooth macadam road quickly it has not sufficient stablility to withstand the ordinary traffic, on this account it is not an economical material for use if any other material is available. A good trap rock is found about a mile farther up the Trask river which could be used to a better advantage on the roads in this vicinity. The rock in the neighborhood of Bester’s Ford five miles east from Tillamook is mostly sandstone and conglomerate. This particular sandstone is entirely unfit for macadam material as it is rather poorly cemented argillaceous sandstone. In these the sand grains are cemented together with a sort of clay material on the whole making quite a friable rock. A conglomerate or “cement rock”, as it is sometimes called, is found 43 near the stream bed at this point. It contains a large amount of good trap rock but is not well situated for economic handling. About one and a half miles farther up the stream there are outcrops of basalt porphyry which will make excellent road material. In the vicinity of Beaver south from Tillamook is quite an extensive outcrop of shaly limestone. This rock has been quarried quite extensively and the material has been used for a number of miles of road in this section. This rock makes a fair material for macadam purposes, it being easily smoothed down into a good surface. It has an excellent binding effect due to the fact that it is comparatively easily ground up under traffic and gives a considerable amount of finer material which as we have already found always aids in the bonding action. Under heavy traffic roads made from this material will be found to wear quite rapidly and if a harder rock could be used with this material as a binder it would give better results. There is a considerable amount of gravels in the streams in this section which is largely made up of good, hard trap rock and might be used to good advantage. Still farther south in the neighborhood between Hebo and Castle Rock are found numerous outcrops of good, hard, rather coarse grained igneous rock, diabase. There are unlimited quantities of this material in this section and will make good road material. It is composed of about 45 per cent feldspar and averages about 30 per cent pyroxene, making on the whole rather a tough, hard rock which will withstand abrasion well. The same rock but finer grained, more on the order of basalt, is found as you approach Hebo from Castle Rock, it being more coarse grained in the vicinity of Castle Rock. On the Clover Dale road, southwest from Hebo there is found an outcrop about one mile east from Clover Dale in a cut in the road side, an excellent hard, dense Basalt. This rock is favorably located. A quarry might be easily opened at this point and accommodate a large section in this vicinity. An outcrop of excellent hard, dense basalt is also found close to Pacific City which will be excellent for road material and can be used to accommodate a large area in this neighborhood. A very large amount of basalt porphyry is found in the vicinity of Estella Falls, two miles southeast from the junction of the Ore Town road with the Estella Falls road. This is excellent material and is found in unlimited quantities and may be of considerable use in the near future as a road building rock. Good hard basalt is also found in the vicinity of Neskowin. The main outcrops being found one and one-half miles north from Neskowin. This is excellent hard, tough material and should be of very great service to this community, as a road rock. North from Tillamook City in the vicinity of Hobsonville on the north side of .Tillamook Bay, there is a point known as Miami quarry. Here is found a more or less weathered diabase. In this rock the pyroxenes are largely changed to cholorite making the rock considerably softer than it was originally, however, the rock is quite firm and gives fairly good results from the standpoint of abrasion and is probably the best Plate ii. — M acadam road construction 45 rock for road material which, could be found in this vicinity. It is very accessible to transportation being situated upon the railroad and on this account will probably be of great service to a considerable portion of Tillamook County. This same rock outcrops just above the town of Hobsonville but seems to be much sotter than in the Miami quarry. The examination was made entirely upon the surface material and it is probably that a quarry might be opened up there in which the material would compare very favorably with the Miami quarry. In the northern part of the county in the neighborhood of Nehalem bay at a point on the south side or the mouth of the Nehalem river in the railroad cut there is exposed an outcrop of fresh, hard, dense diabase, made up largely of feldspar and a goodly percent of pyroxene, an excellent material for road purposes. This material is favorably situated there being a large amount of material in sight and also upon the railroad. This same hard diabase, is found on Coal Creek about one and one-fourth miles above the bridge across North fork of the Nehalem river. This would make an excellent quarry site. Another outcrop of the same material is found on the north fork of the Nehalem road about one-eighth of a mile northeast from the main road from Tillamook to Nehalem. This material is almost identical with the two previously mentioned. The supply of the latter two are probably unlimited. There are certain areas in Tillamook County which are situated at a considerable distance from these favorable outcrops of good material, which will have to rely upon the river gravels for road materials, as there seems to be no available rocks of good quality near enough to be of service. WASHINGTON COUNTY. Washington County does not have its road materials as well dis- tributed as some of the valley counties. The soils have accumulated to such a great depth over a large part of the county that outcrops are very few and far between. When the rocks are exposed in some creek canyon, if quarried for a short distance require such a large amount of stripping that it is very expensive. Two miles west of Gaston is an outcrop of sandstone which has been used to some extent in taht neighborhood as road material. Although this material gives fair results its use would not be warranted if other material could be procured. Near Dilley an outcrop of basalt of excellent quality is found. The quarry site is rather poor, however, and only a limited amount of rock can be obtained without lowering the quarry floor. The Thatcher quarry, situated about three miles northwest of Forest Grove is excellent dense, hard basalt. The only objectionable feature in the quarry is the great amount of over burden which requires stripping as fast as the rock face is quarried. In the extreme southeastern part of the county are the most important outcrops of trap rock found. About five miles southeast of Hillsboro are some outcrops of basalt and although no extensive quarries have 46 been opened up, good quarries can without doubt be located here with a comparative small amount of stripping. Farther to the southeast are a number of good basalt outcrops, the most important being in the neighborhood of Tonquin on the Oregon Electric Railway. One-fourth of a mile north of 'the station is an excellent location for a quarry, and it is very probable that a large part of Washington County can be accom- modated from this point. Just east of Tualatin near the Southern Pacific Railroad is another good quarry site from which considerable material might be distributed. Just east of the station at Tigard is a good outcrop of porphyritic material which will make excellent road material. The tunnel which is being driven in the neighbrohood of Phillips has passed through good, dense basalt for 950 feet and it is possible that some favorable localities might be found in this vicinity for quarries. YAMHILL COUNTY. Yamhill County is more fortunately situated with reference to good road building rocks than either Washington or Polk. There are a number of good trap rocks well distributed over the county. The Willamette river gravels are available along the southeast boundary line and will accommodate a considerable area tributary to it. One-half mile north of the town of Amity is an outcrop of hard, dense basalt very profusely fissured and broken up similar to the Ewald quarry south of Salem, making the rock easier to quarry than it other- wise would be. From this point northeast for a distance of four or five miles, is a range of hills in which indications are that numerous outcrops could be found. A quarry is located four miles east of Whiteson at the extreme northeast point of this range. The rock in this quarry is identical in every respect with that found in the Amity quarry. This rock gives excellent tests as a road metal. About three-fourths of a mile southwest of Bellevue is a quarry of altered basalt. This rock is considerably softer than the average basalt and on account of a great amount of secondary calcite being developed in it, it is shown on the map accompanying this bulletin as limestone. This rock will make a good road where the traffic is not too severe. If required for a road which has a great amount of heavy travel it would be good policy to select a harder rock for the main mass of the road and use this rock as a binder. About three miles northwest of Bridewell on a prominent point of hills is found a good outcrop of hard, dense basalt, which would make an excellent quarry site. The McMinnville quarry west of the city exposes a face of fine dense black basalt which will make as good road material as can be found anywhere. An outcrop of diorite is found at a point about five miles northwest of McMinville near Dawson Creek. This rock is coarse grained and although it does not give as good tests for road material as the fine grained basic rocks it is well adapted for the construction of roads and should give good service. About two and one-half miles west of Carlton are found a couple of quarries of good. 47 hard, tough diabase which make excellent material for macadam pur- poses. About two and one-half miles west of Yamhill is another outcrop of diabase very similar to the quarries west of Carlton. These should do good service in this vicinity in supplying road materials. Two miles north of Lafayette are found some excellent quarries showing dense black basalt. This rock is considerably fissured, similar to that in the Amity quarry before mentioned. Three miles west of Newberg is a hill upon which are found outcrops of dense, fine grained basalt. A quarry is opened up on the southwest side of the bill and shows somewhat the same fissured structure found in the Amity and Lafayette quarries. About one mile north and one-half mile east of Newberg is a quarry of the same dense, hard basalt. It is an excellent site where a large amount of rock may be obtained, and is especially desirable since it is close to the railroad. Just south of the town of Newberg across the creek on the road to Dayton, is found an outcrop of good, hard quality basalt. It is not however a good quarry site for obtaining a large amount of rock. SUGGESTIONS FOR SELECTING A QUARRY SITE. A few suggestions as to important points to be observed in the intelligent selection of quarry sites may be of assistance to the road builder. Careful preliminary examination before selecting a site for the quarry cannot be too strongly emphasized, because the expense of several days or weeks of careful prospecting will often be offset by a single days expense in needlessly stripping a heavy overburden in an unfavorable location, or by a single days expense in extra hauling. With all due respect to the road builders, in a number of localities over the Willamette Valley the counties are paying a heavy tax of incom- petency or lack of careful preliminary examination before selecting the most advantageous point for the location of the quarry. In this con- nection it should be stated that no county or community which is contemplating any considerable amount of road building can invest their funds in a way that will bring greater results than in intelligent engineering management. Very few people seem to understand thq duties or office of the road engineer. The engineering department of the Oregon Agricultural College is pursuing as a policy, the belief that the road engineer should not only be thoroughly familar with the details of surveying, draining, grading and general construction, but he should also be able to go into the field and intelligently select all the most available quarry sites which will give good road materials, and to manage all the details of the work with best financial results. To do this he must be able to determine the extent of the different rock ledges, their adaptability for road metal, to estimate accurately the comparative cost of opening up quarries at different points in a community, to intelligently plan the equipment of quarrying and crushing plants, to estimate the cost of quarrying, crushing and hauling, and in view of all the above details to prosecute PivATE 12. — Good rural schools and good roads go hand in hand. Marion County. 49 the work in an efficient manner and ultimately obtain from it the most economical results. This evidently can only be accomplished by employ- ing the trained experienced highway engineer and giving him full charge of the work, unhampered by lack of funds. We would not attempt here to give all the details of intelligent selec- tion of quarry sites, for as has already been intimated, this includes a large proportion of the road engineer’s training and can only be attained by a careful study of some of the fundamentals of the principles of geology. We can, however, give some useful suggestions which should be of service to the people who are now doing the road building. In the discussion of the general geology of the Willamette Valley it has already been noted that the south or west slopes of hills usually have a less depth of soil and therefore more outcrops of fresh rock than the east and north sides, for the reason that the wind has a better chance at these slopes and carries the soil away as fast as formed. For this reason more numerous outcrops are found in the first foot hills on the east side of the valley than the corresponding ones on the west side of the valley. In almost every case the south or west slopes of hills will be found most advantageous for quarry sites. The exceptions to this statement being where stream erosion exposes the north or east sides of the hills. It should be borne in mind that canyons are almost always formed by the erosion of the streams which occupy them, hence outcrops may be expected upon the sides of stream canyons. In general, the steeper the canyon side the less the depth of soil. Very often the rock, when covered by soil upon the canyon side, will be found freshly exposed in the stream bed, thus giving a clue to the grade of material which could be opened up in a quarry on the canyon side. On account of the necessary expense in opening and installing equip- ment at a quarry it is probable that quarries will not usually be located closer to each other than two miles, even if a number of available quarry sites should be found. On the other hand, it will be found that in most cases five or six miles will be the maximum distance between quarries where outcrops are available, because the expense of haul with teams will be sufficient to warrant the expense of opening and equipping a new quarry. Other means of mechanical transportation such as railroad or auto trucks will of course vary this maximum limit. The principles of rock weathering are very important as an aid in the selection of a quarry site. It will not be possible to give many details along this line here, but some useful hints may be given. A large proportion of the low hill lands in the Willamette Valley are made up of the basic igneous fine grained rocks known as trap or trap rock. These rocks are rich in iron and as they decay, this iron is changed from the original silicate to the secondary oxide, the natural color of which is red or brown. Thus the soils derived from these rocks are painted red or brown and give rise to a large amount of the “red hill lands” so common in the Willamette Valley. On this account then it is usually easy to locate trap rock outcrops, but these outcrops 50 are usually hidden by a greater or less depth of soil. By applying some of the principles already mentioned the most favorable points upon the hill can be selected. It is of the utmost importance in selecting the proper site for the quarry that the location of the crushing plant be considered. If possible the crusher should be placed so that its mouth is just below the floor of the quarry in order to insure convenience in handling of material. The writer has observed a number of quarries in different parts of the valley where the material from the quarry is wheeled up a steep incline and dumped upon a platform from which the material is fed into the crusher. This extra work could have been obviated by placing the crusher in a pit. Pushing a car or wheelbarrow load of rock up an incline is excellent exercise but not good engineering management. One instance of the location of a quarry may be noted as a typical example of poor management. The excavation was made on one side of the hill, developing a pit some ten or twelve feet deep. A road way was main- tained down into the pit, around to the opposite side of the hill and the rock shovelled from the wagons to a platform after which it was fed into the crusher. The reason given for such an arrangement was to prevent damage to the crusher by blasting rock upon it. GRAVELS Ii\ THE WILLAMETTE RIVER. The Willamette river with its main tributaries winding through the Willamette Valley is without doubt the most important good roads asset that we posses. We have already seen in the description of the general geology of the Willamette Valley that the valley floor is bounded on all sides by foothills composed almost entirely of igneous rocks, and what is more the best grade of igneous rocks, namely trap rocks. Since the gravels carried by any stream or found upon its bed must necessarily be derived from the outcrops of rock through which it runs, it would follow that the gravels will always be of the same material as the out- crops of rocks in place through which the stream passes. For the past thousands upon thousands of winters, the friendly old Willamette has been carrying and rolling these fragments of rock along its bed leaving in its train an immense amount of road material. On this account we have a continuous deposit of gravel over 200 miles in length with probably an average width and depth of 300 feet and 6 feet respectively, winding through the central part of the valley. In other words, the Willamette riyer contains more road material than would be needed to surface all the roads in the state of Oregon 15 feet wide and 6 inches in depth. Upon careful examination at a number of different points along the Willamette river these gravels are found to be over 90 per cent trap rock. These gravels in the bed of a stream will vary considerably in size at different points in the same stream, owing to the varying velocity of the current at different points. At rapid points in the stream they are invaribly many times the average volume of those in comparatively 51 smooth portions of the stream. The size of the gravel in a stream bed varies also with reference to its distance from the head waters. This is due partly to the fact that the velocity of the stream is greater near the head waters and partly to the fact that the individual gravel in the stream near its source have been subjected to much less abrasion than those farther down. In the light of the above discussion the gravels in the Willamette river bed at Eugene are found to be much coarser than at Portland, also that these gravels vary a great deal in size at different points in the same locality. Since this gravel is over 90 per cent trap rock how about its qualifications for a road material? It is a well known fact among practical road builders that gravel is not satisfactory for a road surfacing material as crushed rock of good quality from the quarry. The reason for the difference between the two as usually given, is on account of the inferior material of the gravel. We have shown in the case of the Willamette river gravel that the material is as good as the best, being nearly all trap rock, hence we will have to account for the diffficulty with the gravel along other lines. This is found in the rounded shapes of the gravel. It lacks the wedging characteristics that the angular crushed rock possesses, already discussed under cementing or binding value of rocks. Clean rounded gravel will not pack or wedge together like angular fragments of crushed rock, in fact any practical road builder will attest to the fact that gravel cannot be rolled with the road roller until some binding material is added, such as gravel screen- ings or crushed rock screenings, but will push ahead of the roller and allow it to sink down through the gravel mass by displacement. This then is the vital difference between a gravel and macadam road; one will pack by virtue of the shape of its angular fragments alone, while the other depends entirely upon the binding material in the voids to make it pack together into a good, firm road. A well made gravel road is an excellent road, however, and although it required a greater thickness of gravel to support the same load as the crushed rock road, yet it has sufficient strength for any ordinary traffic, and gravel roads often give practically as good results as the best of macadam. Again referring to the coarser gravels in the Willamette river is there any good reason why these gravels cannot be dredged out of the river, crushed and used for building macadam roads in the vicinity of the river? There are numerous places along the river where these gravels will range in size from a man’s fist to his head, and if crushed will be broken into from 5 to 50 nieces each. This material will then be equally as good for macadam material as that obtained from the quarry. This i? a very important factor from the standpoint of economy for two reasons; first, by reference to the map showing distribution of rock material it will be seen at once that there are comparatively few outcrops of good road making rocks near the river, but that they are located on the first rim of the foot hills bounding the valley. Now since the river winds its way approximately through the center of the PiyATE 13. — Crushing plant. Ewald quarry, Marion county. 53 valley it becomes the most important factor in equalizing the distribution of available materials in the valley. As is pointed out in the discussion of cost data, transportation is a very important item in the cost of construction of the average macadam road. Secondly, the cost of pre- paring these coarse gravels for macadam materials as compared with the cost of preparation of ledge rock, can be considerably reduced. With a reasonably good dredging apparatus and good engineering management, crushed gravel can be delivered into the wagon for at least one-half the cost of average condition in the quarry. Some road builders object to this added expense of crushing, and advocate using the finer gravel screened without crushing. In answer to this objection it should be noted that the additional expense of crushing is very small and that the advantages will more than offset this expense. If the work is to be quite extensive it will be evident at once to the experienced engineer, that in order to screen and load gravel economically he must provide a mechanical elevator and screens both operated by power, delivering the gravel into bunkers from which it can be delivered by gravity directly into wagons. Now by adding the crusher to che equipment we have not necessarily reduced the capacity of the plant and have added only a small additional expense in extra power and repairs. Tn return, if coarse gravel is used, we get crushed rock as a product thereby reducing the amount of material required for the construction of the road. We are also insured a more uniform product, and are relieved of the exoenso of discarding the coarse gravel which would pass over the screens in the gravel pla.nl without the crusher. On the whole the crusher in such a plant will be found quite an economical factor if much gravel is to he handled, and absolutely indispensible where the gravel is coarse. GENERAL OBSERVATIONS AND SUGGESTIONS. Among the large number of road builders in the valley, we would expect to find different opinions as to the best methods of road con- struction. It is the purpose of the following discussion to correct as far as possible some of the prevailing erroneous ideas with reference to road building. The time has arrived in the Willamette Valley when we should get together and stand as a unit for up-to-date, systematic building of permanent roads. There are a number of road builders in the valley who apparently are of the opinion that a heap of gravel dumped along the middle of the road and driven over until packed makes a good road. Gravel roads make good roads but there is a right and wrong way to construct them. The road bed should always be well drained, carefully prepared and the subgrade rolled and good substantial shoulders formed. The gravel should always be screened and the respective sizes put on separately; and the whole mass rolled and well bound with sufficient binding material. Under these conditions there will be no more material used than in the old fashioned gravel road, while the extra labor and ex- pense will be more than offset by the satisfaction to be derived from 54 the up-to-date gravel road. It is the practice in a number of localities in the valley to place a quantity of uncrushed rock on the road, depending upon the traffic to do the crushing. This, as anyone will testify, is an inconvenient as well as expensive way of crushing rock. There are communities in which great pains are taken to crush the rock and to screen it separating the different sizes after which the whole mass is usually laid upon a crown in the road, without any preparation of the road bed having been made to receive it. In this method, traffic is again depended upon for packing or consolidating the mass. The result is that a large part of the crushed rock is worked off at each side of the road by the traffic, and the central part of the road is soon worn into ruts. Although this method is an improvement over the gravel heaps or the loose uncrushed rock road, it is still very un- satisfactory. A small amount of additional funds invested in a road roller, as well as some attention paid to preliminary preparation of the road bed to receive the crushed rock, would pay handsome dividends on the investment. In still other localities the practice has been observed of placing upon a well prepared road bed a foundation of a layer of larger rocks. These rocks are often from eight to ten inches in diameter. Crushed rock is then spread over the boulders and rolled in the ordinary way. This method makes an excellent road, but not an economical one, for the reason that almost twice as much material as is needed is used. It is evident that the boulder foundation in such a road contains an ample amount of material, if crushed, to construct the best of macadam roads. The road equipment in some counties includes three or four crushers and one roller. The idea seems to prevail that a number of crushers are required to keep the roller busy. Under these conditions the road rarely receives a sufficient amount of rolling to make it first class. The ordinary size crusher, nine inch by fifteen inch opening, if used to its capacity will furnish from sixty to seventy-five cubic yards of crushed rock per day. If the macadam road is properly rolled it will be found that from three hundred to four hundred square yards is all that any ordinary size road roller will be able to complete in a day. If the macadam is six inches thick this makes from fifty to sixty-five cubic yards. It is evident that the ordinary crusher will keep a roller busy. It is the practice of some road builders to place tile drains underneath the surfaced portion of the macadam road. This practice is not only a useless expense but a positive detriment, as the tile tends to destroy the capillary action of the water and dry out the road surface, destroying the binding action. This same principle is often noted in the surface of macadam roads over a high fill. Under these conditions the surface ravels at this point more readily during the dry season than in the less elevated portions of the road. If the ditches on either side of a macadam road are ample in size and grade to carry the water, and are 55 from fifteen inches to eighteen inches below the crown of the road the sub-grade will be amply drained. Another very common fault in road construction observed in the valley is a tendency to put too much crown upon the macadam surface. This results in the travel being confined to the center of the road, because of the discomfort experienced in driving on one side. Thus the center of the road wears much more rapidly than the sides, and is soon rutted. Fig. 6 shows the United States object lesson road near Salem where the crown does not exceed one half inch per foot. Note the fact that the view shows no main traveled track on any part of the surfaced road. Two very common errors in the construction of macadam roads are using an insufficient amount of fine material or rock screenings as a binder, and in not using water in sufficient quantities for flushing during the rolling process. The office of this flushing process is to thoroughly pud- dle the mass by working the finer particles into the voids and thereby bring- ing about conditions for more perfect capillary action. (See discussion of cementing value of rocks). These are vital points in road construction and no road builder can ignore them and succeed. COST DATA. The statistics on the cost of general road construction is a variable quantity, being approximately inversely proportional to the good judg- ment and management of the road engineer. However, some cost data of roads built in the Willamette Valley will be of interest. The following estimates were received from H. B. Chapman, superin- tendent of Multnomah county, showing the average results covering 125 miles of macadam road built in that county. Grading averages about 25 cents per yard. With the average prevailing conditions in Multnomah County this would mean a cost of $500 to $750 per mile. Cost of crushing runs from 25 cents to $1.25 per cubic yard. This includes stripping, drilling and blasting. The number of yards of crushed rock used to the mile on a 16 foot road bed 6 inches deep consolidated is 2500 cubic yards. Hauling costs about 25 cents per yard mile. Three miles being the maximum haul. Cost of preparing the road bed to receive the rock when road bed is 16 feet wide, 6 to 8 inches deep, finished macadam, with water near by for flushing, is from 7 to 10 cents per square yard or 25 cents per cubic yard of rock laid. Summary of Data of Multnomah County. Clearing, etc., per mile $ 100 to $ 500 Grading 500 to 750 Crushing rock 1,875 to 3,750 Hauling 625 to 1,875 Total 3,100 6,875 PiyATE 14. — Germantown road near Portland. Showing proju r 1 Plate 15. — Liberty road, Marion County, 58 The following is a specific case of Marion County’s expense in road construction as taken from the records in the County Clerk’s Office. Expenses incurred in building a little over a mile of the Turner Road. A large amount of volunteer labor was performed, no account of which has been kept; to offset this some five miles of additional road bed was prepared at the same time. Expense of moving crusher and roller $ 26.73 “ “ Engineers at rock crusher plant 279.25 “ “ powder 35.10 “ “ repairs on crusher and other tools 162,30 “ “ rock bin at Turner plant 136.33 “ “ wood used by the crusher and roller 198.75 “ “ lumber used at Turner crusher 32.54 “ “ labor on Turner road 2,071.00 “ “ surveying Turner road ' 53.45 “ “ new tools 9.55 “ “ advertising for the Turner road 16.15 “ “ moving tools to county shed 3.00 Total $3,030.17 The above does not take into account the labor that was furnished by the convicts who were employed to do a considerable portion of the labor. The expense of the convict camp is as follows: Provisions for the Convict Camp $ 891.70 Fixtures for the Convict Camp 38.90 Bunk house 138.40 Guarding convicts 725.70 Tobacco for convicts 48.65 Total $1,843.43 The number of days of convict labor performed were given as 1543. If we allow nothing for the wage of the convict labor as above, the cost of the finished road would total $4,873.69 per mile. On the other hand if we allow $2.50 per day for the 1543 days of labor and deduct the $1,943.43, the cost of feeding and guarding the convict camp as above, the total mile of road will cost about $6,887.67. The convict labor thereby saving the county about $2,014.07 on the mile of road built. The following is an itemized list of expenses incurred at the Sublimity rock crushing plant for the year 1908: Expense of moving crusher from Turner to Sublimity $ 76.00 “ “ repairs on crusher 178.10 “ “ new tools 101.01 “ “ tool steel 41.70 “ “ coal 10.40 Miscellaneous expense at the plant 24.05 59 Nails 7.30 Expense of iron 4.94 “ “ repairs on tools 7.50 “ “ oil 10.40 “ “ powder 76.00 “ “ labor running the crusher 382.33 Total $919.71 Expense of guarding convicts $ 427.5fc “ “ provisions for convict camp 459.00 “ “ tobacco for convict camp 40.71 “ “ cook for convict camp 14.00 “ “ fixtures and incidentals for for the camp 55.10 “ “ clothing for convicts 1.30 Total $1,917.32 Enough rock was crushed for one mile of road, or about 2000 cubic yards. Approximate number of days of convict labor performed was about 1120, for which the state was paid five cents per day, $56.00. If we deduct the cost to the county of feeding and guarding the convicts and allow $2.50 per day for the 1120 days work which they furnished to the county, the cost of the rock would approach or approximate $3719.71. This approaches the maximum cost of crushing enough rock for one mile of road in Multnomah County. FREIGHT RATES ON ROAD MATERIAL. The following table shows the rates authorized by the different railroad companies of the valley for the hauling of sand, gravel, crushed rock and stone: 5 miles and less 2c per 100 lbs. Over 5 miles and not over 15 mines 3 c 44 100 “ “ 15 44 44 44 “ 25 44 3Y2C fee 100 “ " 25 44 44 44 “ 35 44 4 c « 100 “ “ 35 “ 44 44 44 45 “ 44 100 44 “ 45 (4 44 44 44 55 “ 5 c 44 100 “ “ 55 4€ 44 44 44 65 44 “ 100 44 “ 65 44 44 44 44 75 44 6 c 44 100 “ 75 44 44 44 44 85 “ 100 “ “ 85 “ 44 44 44 95 44 7 c 44 100 “ “ 95 44 44 “ 44 105 “ 7V2C 100 44 The above rates apply on car load lots and are subject to a minimum rate based on the carrying capacity of the car used. Special rates are sometimes quoted to counties. 60 SUMMARY AND CONCLUSION. In the preceding pages it has been pointed out that in order to intelli- gently determine the value of a rock for road material, it is necessary to understand its structure, as well as the important physical properties of its constituent minerals. It has also been shown that the abrasion test for determining the percentage of wear, is by far the most important mechanical test, and that the cementing test which has been given so much weight by some authorities is of no practical value. It has also been shown that the so-called cementing action in macadam roads is due to an interwedging effect between the rock particles, and the binding power is due to capillarity and surface tension of water. It has been pointed out that the gravels in the bed of the Willamette river are most fortunately located in the valley, since these gravels are excellent material and can be dredged, crushed and put on the road with much less expense than quarry rock. It has been shown that the principles of rock weathering are of very great importance in determining the value of rocks as road metal, and in the selection of quarry sites. The Willamette valley is probably better supplied with excellent road material than any other important agricultural district of equal area in the country. GLOSSARY OF SCIENTIFIC TERMS USED IN THIS BULLETIN. ACID. — Containing a high percentage of silica-bearing minerals. Op- posed to basic. AEOLIAN. — Sediments carried and deposited by the action of the wind. AMPHLBOLE. — See Hornblende. ANDESITE. — A very fine grained volcanic rock (lava) consisting when fresh essentially of feldspar and pyroxene, hornblende or dark colored minerals. ARGILLACEOUS. — Originally clayey in composition. BASIC. — Containing a low percentage of silica and a relatively high percentage of lark-colored, iron-bearing minerals (hornblende, pyroxenefi etc.) BASALT. — A very fine grained volcanic rock (lava), dark in color, con- sisting of the ferro-magnesian minerals. CALCAREOUS. — Containing calcite. CALCITE. — Carbonate of lime (CaC03). CHERT. — A variety of silica. CHLORITE. — A greenish, soft, platy mineral. Chemically a silicate of aluminum and magnesium (or iron). Often a decomposition product of hornblende or pyroxene. CONGLOMERATE. — A rock consisting of rounded pebbles or boulders cemented together. CRYSTALLINE. — Made up of crystal grains. CLEAVAGE. — The breaking of a mineral along definite plains which is due to geometrical moleculor arrangement. DIABASE. — A dark colored igneous rock consisting, when fresh, mainly of plagioclase feldspar and pyroxene, usually with some magnetite (iron oxide). Normally shows a characteristic interlocking of crystal grains. DOLAMITE. — A carbonate of magnesia and lime. Resembles limestone. DIORITE. — A granitic igneous rock consisting, when fresh, of plagio- clase feldspar, hornblende, pyroxene and in some cases with a small amount of quartz. Usually darker in color than the granites. EXTRUSIVE. — Igneous rocks that are poured out on the surface of the earth as in the lava flows. EROSION. — The wearing away of portions of a rock mass by such natural agencies as stream, ice, or wave action. FELDSPAR. — The feldspars are silicates of aluminum with various amounts of potash, soda, and lime. Hard minerals with good cleavage in two directions. Usually white to pink or gray in color. FOLIATED. — A rock which is made up of parallel groups of minerals such as mica. GABBRO. — A coarse grained crystalline rock composed, when fresh, mainly of plagioclase feldspar and pyroxene. Differs from diabase in possessing a granitic rather than an interlocking or diabasic structure. GNEISS. — A coarsely foliated or laminated rock. 62 GRANITE. — An igneous rock usually consisting, when fresh, of a crys- talline aggregate of quartz, feldspar, mica, or hornblende. Usually gray to pinkish in color. GRANITIC. — Granite-like in composition and texture. HORNBLENDE. — A group of moderately hard minerals, usually dark green to black in color. Silicates of lime, magnesia, iron, and alumina. A common constituent of diorites and many granites. IGNEOUS. — A term applied to rocks that have soldified from a molten condition. INTRUSIVE. — Rocks that have been forced up from depths into the solid crust of the earth while in a plastic, heated condition. JOINTS. — Rather large and continuous fracture planes in rocks, usually steeply inclined. KAOLIN. — A variety of clay, white in color. Alteration product of feldspars. MAGNETITE. — Magnetic iron ore — iron oxide; hard, metallic, black, and opaque. METAMORPHIC. — A term applied to rocks whose constituents have been recrystallized either with or without chemical change and which have been subjected at some time to heat and pressure. MARBLE. — Metamorphic limestone. MICA. — Minerals distinguishable by a very easy cleavage whereby they can be split into very thin elastic leaves. All micas are silicates of aluminum, containing alkalies, with oxides of iron and magnesium. MICRO-CRYSTALLINE. — Crystals can only be seen under the micro- scope. ORTHOCLASE. — Potash feldspar. The common feldspar of granite. ORGANIC. — Being formed by plant or animal life at some time. PLAGIOCLASE. — A name applied to a group of feldspars which are silicates of alumina and soda or alumina with both soda and lime. Often distinguished from orthoclase by the striations, or ap- parent scratches on the cleavage face. PORPHYRITIC.— Possessing the texture of a porphyry. PORPHYRY. — Any rock showing crystals embedded in a groundmass showing much finer grain. PYROXENE. — Hard minerals, usually dark green or black in color. Silicates of magnesia with variable proportions of iron, lime, and alumina. Distinguishable from hornblende by cleavages inter- secting approximately at right angles rather than at an acute angle. PETROGRAPHIC. — From the study of a thin section under the micro- scope. QUARTZ. — Oxide of silicon, Hard. Usually white to gray; fractures irregularly; a common constituent of granites. QUARTZITES. — Rocks that were originally sandstones, the pores having been subsequently filled by quartz through deposition by percolating waters. A metamorphic sandstone very often forms a quartzite. 63 RHYOLITE — A type of extrusive igneous rock. Having the same miner- alogical composition as the granites but not the coarse crystalline texture. Usually light in color. SANDSTONE. — A rock originally a sand, but subsequently compacted and the grains partially cemented together so as to form a coherent rock. SCHIST. — A crystalline rock having a foliated or parallel structure and splitting easily into slabs or flakes, less uniform than in slate. SECONDARY. — A term applied to rock minerals which are derived partially or completely from the alteration of other minerals in the rock. SEDIMENTARY. — A term applied to those rocks that are formed by accumulations derived from other rocks that may be laid down by the action of wind, water, or by chemical precipitation. SHALE. — A bedded rock formed by the consolidation of muds, silits, or clays. SILICA. — Oxide of silicon. Quartz is the commonest form of silica. SILICEOUS. — Rich in silica or silica-bearing minerals. SLATE. — An argillaceous rock which is finely laminated and fissile, either due to very easy and uniform parting along bedding planes or (more properly) to cleavage planes developed as a result of compression (as in roofing slate.) SERPENTINE. — A soft green mineral with a greasy feel. A secondary mineral formed from pyroxene or amhibole. SYENITE. — A granitic rock having no quartz. TRAP. — A general term for igneous rocks of the dark basic type. Such as the basalts or diabases. TRACHYTE. — A compact igneous rock consisting, when fresh, mainly of potash feldspar in small lath-shaped crystals, with various amounts of plagioclase, biotite, pyroxene, and hornblende. TALC. — An alteration product of pyroxene and amphibole. Usually white to greenish gray in color. Closely allied to Serpentine chemically. A hydrogen magnesium silicate. Has a greasy feel like serpentine. TERTIARY. — One of the recent geological epochs. The Tertiary Period is further divided into the Eocene, Miocene, Pliocene, and Pleistocene in order of time. TUFF. — A volcanic product of the explosive type. Fine mineral aggre- gates that accumulate after the settling of the volcanic products blown into the air. VOLCANICS. — A name applied to igneous rocks which have been deposited at the surface of the earth either as flows of lava or as bedded masses composed largely of lava fragments. They may be acid or basic. r